The search for novel compounds with a musky odor has increased steadily in the last few years, as a result of the privileged position that this type of fragrant compounds occupies in modern perfumery. Several hundreds of these compounds are known today, forming a rich source of structural information which has lead certain authors to establish qualitative rules intended for predicting which types of chemical structures are more likely to provide good quality musky compounds, judging from the intensity, the tenacity or the elegance and individuality of their odor note. Although these rules can prove helpful for finding a few more or less interesting compounds, they do not constitute an ersatz for the researcher's inventive mind, which reveals itself all the more pertinent when it follows, by intuition, a discovery path that would have been discouraged by said principles built on the basis of the known prior art. As it will become apparent shortly, the present invention is just an example of this.
It is generally accepted that, in musky aromatic compounds whose benzene ring possesses an acyl group substituent, sterical hindrance of this functional group can lead to loss of odor [see, for example, M. J. Beets, Structure-Activity Relationships in Human Chemoreception, 207, ASP Ltd. London (1978)]. Thus, any attempt to further substitute the benzene ring in the following basic structural skeleton for the aromatic compounds of interest ##STR15## would have been discouraged from the start. There are several musky compounds already known which obey this basic structure, the best known representative thereof being Tonalid.RTM. (origin: Polak's Frutal Works Inc.), which has the following structure ##STR16## and is well appreciated in the perfume industry.
Unlike what could have been expected from prior art predictions, we have now discovered that further methyl and methylene groups can be incorporated in position a or b (see skeleton above) of the benzene ring without observing any prejudicial effect on the odor properties of the resulting compounds, in spite of the ensuing perturbation of the functional group's environment. On the contrary, several excellent novel musky compounds have thus been discovered.